Japan on Tuesday lifted a self-imposed ban on weapons exports, introducing new rules covering the arms trade in a move supporters say will boost Tokyo's global role, but which unnerved China.

The cabinet of Prime Minister Shinzo Abe approved a new plan that replaces the 1967 blanket ban, Chief Cabinet Secretary Yoshihide Suga told reporters.

Under the policy, arms sales are banned to conflict-plagued countries or nations that could undermine international peace and security, the sales must contribute to international peace and boost officially pacifist Japan's security.

"Under the new principles, we have made the procedure for transfer of defence equipment more transparent. That will contribute to peace and international cooperation from the standpoint of proactive pacifism," Suga said.

"And we will participate in joint development and production of defence equipment," he said.

Japan's post-World War II constitution, imposed by the US-led occupiers, banned the country from waging war.

That pacifism was embraced by the population at large and two decades later a weapons export ban was introduced.

Supporters hope the relaxation in the policy will boost home-grown arms manufacturers at a time of simmering regional tensions including a territorial row with China and fears over an unpredictable North Korea.

The new rules could allow Tokyo to supply weaponry to nations that sit along important sea lanes to help them fight piracy -- an important strategic consideration for resource-poor Japan.

Japanese arms could potentially be shipped to Indonesia as well as nations around the South China Sea -- through which fossil fuels pass -- such as the Philippines, which has a territorial dispute with Beijing.

Japan already supplies equipment to the Philippines' coastguard, an organisation that is increasingly on the front line in the row with Beijing.

Any move to bolster that support with more outright weapon supplies could irk China, which regularly accuses Abe of trying to re-militarise his country.

On Tuesday, Chinese foreign ministry spokesman Hong Lei said Beijing was paying close attention to the relaxation of Tokyo's arms ban.

"The policy changes of Japan in military and security areas concern the security environment and strategic stability of the whole region," he said at a regular press briefing in Beijing.

"Due to historical reasons, Japan's security policies are always closely followed by regional countries and the international community."

China and Japan are at loggerheads over the ownership of a string of islands in the East China Sea, while Beijing is also in dispute with several nations over territory in the South China Sea, which it claims almost in its entirety.

The Tokyo-Beijing diplomatic relationship has long been marred by Japan's expansionist romp across Asia in the first half of the 20th century.